KHONDAB, Iran — Iran inaugurated a heavy-water plant Saturday, expanding its nuclear program only days before a U.N. deadline that threatens sanctions unless Tehran curbs activities the West fears are meant to make atomic weapons.

The move was the latest defiance by Iran to concerns expressed by the U.N. Security Council. Hard-line President Mahmoud Ahmadinejad shrugged off the possibility of sanctions, insisting his country would not slow its nuclear ambitions.

“We tell the Western countries not to cause trouble for themselves because Iranian people are determined to make progress and acquire technology,” Ahmadinejad said after opening the plant.

He stressed his government’s contention that the nuclear program is peaceful — intended only to produce fuel for nuclear reactors that would generate electricity. The U.S. and its allies accuse Tehran of seeking to develop atomic arms.

“There is no discussion of nuclear weapons. We are not a threat to anybody, even the Zionist regime (Israel), which is a definite enemy to the people of the region,” said Ahmadinejad, who has drawn strong international criticism for saying Israel should be wiped off the map.

Deadline on ThursdayThe Security Council has given Iran until Thursday to suspend another part of its nuclear program — the enrichment of uranium, which can produce both reactor fuel and material usable in nuclear warheads.

Iran said earlier in the week it is open to negotiations but it refused any immediate suspension, calling the deadline illegal.

The U.N. nuclear watchdog, the International Atomic Energy Agency, is to report to the council on Iran’s program by mid-September. If IAEA chief Mohamed ElBaradei’s report finds enrichment is continuing, the United States and some in Europe are likely to push for sanctions.

Tehran appears to be counting on sanctions being blocked by its allies in Russia and China, major trade partners that as permanent members of the council hold veto power over its actions.

Russian Vice Premier Sergei Ivanov said Friday that it was too early to consider imposing sanctions and that his country would press for a diplomatic solution to the standoff.

The ceremony at the Khondab heavy-water plant, which has been operating since 2004, was largely a symbolic gesture underlining Iran’s determination to ignore international pressure. The plant’s top official, Manouchehr Madadi, said the facility can produce up to 16 tons of heavy water a year — double the amount it previously made.

The U.N. deadline does not demand a halt to operations at the plant or a nearby reactor that Iran is building to use the heavy water, focusing on what is seen as the more urgent concern of uranium enrichment.

Still, the West repeatedly has called on Iran to stop work at the heavy-water facility, fearing it could be used as a second track toward building warhead.

Uranium without the enrichmentHeavy water contains a heavier hydrogen particle that allows a nuclear reactor to run on the natural uranium mined by Iran, without undergoing the enrichment process. But the spent fuel from a heavy-water reactor can be reprocessed to extract plutonium for use in a bomb.

The 40-megawatt reactor, due to be finished in 2009, could produce enough plutonium for a nuclear weapon each year, experts have said.

Reactors fueled by low-enriched uranium use regular — or light — water in the chain reaction that produces energy. But the process that produces such fuel can also enrich uranium to a higher level of purity that can be used to build a weapon.

The inauguration of the heavy-water plant drew a quick response in Israel.

Legislator Ephraim Sneh of the Labor Party, a partner in Israel’s governing coalition, warned that the plant marks “another leap in Iran’s advance toward a nuclear bomb.” He said Iran can’t be trusted and Israel must “prepare itself militarily.”

Both the water plant and reactor are ringed with anti-aircraft guns to guard against air strikes, sitting at the foot of mountains outside Khondab, 200 miles southwest of Tehran. Parts of the unfinished reactor complex are believed to be underground for further protection.

West's demand refusedOn Tuesday, Iran responded to package of incentives from the Security Council’s five permanent members and Germany aimed at enticing it to halt enrichment. Tehran said it was willing to talk but would not agree to the West’s demand that it first suspend enrichment.

Ahmadinejad said Saturday that Iran would pursue its right to develop nuclear technology even if sanctions are imposed.

“They may impose some restrictions on us under pressure,” he said. “But ... will they be able to prevent a nation’s access to progress and technology?

“They have to accept the reality of a powerful, peace loving and developed Iran. This is in the interest of all governments and all nations whether they like it or not.”